percy-puppeteer on GitHub

Visual regression testing for Puppeteer tests with Percy.

Installation

📘

Make sure you have completed Setup of your CI service first. You can also test Percy in your local development environment.

Install @percy/puppeteer using npm:

npm install --save-dev @percy/puppeteer

Or using yarn:

yarn add --dev @percy/puppeteer

📘

These docs apply to version 1.0.0 or later. Previous versions of @percy/puppeteerare incompatible with what is described in this document.

Quick Setup

These are the minimal steps required to add visual testing to your existing Puppeteer code:

1. Import percySnapshot() into your file: const { percySnapshot } = require('@percy/puppeteer')
2. Call percySnapshot(page, <snapshotName>) wherever you want to save a snapshot.
3. Wrap your script or test run command in percy exec --, e.g. percy exec -- mocha.

Next, we will go through each of these steps in detail.

Setup

In order to start creating snapshots from your Puppeteer scripts or tests, you'll need to import the percySnapshot() function from the @percy/puppeteer package. You will need to do this in each file from which you want to take snapshots:

const { percySnapshot } = require('@percy/puppeteer')

You will then use percySnapshot(...) to generate a snapshot:

describe('Integration test with visual testing', function() {
  it('Loads the homepage', async function() {
    const browser = await puppeteer.launch()
    const page = await browser.newPage() 
    await page.goto(TEST_URL)
    await percySnapshot(page, this.test.fullTitle())
  })
})

Finally, wrap your script or test runner command in the percy exec command. This will start a Percy agent to receive snapshots from your tests and upload them to your Percy dashboard. For example, if you are using Mocha for your tests, your new test command becomes:

percy exec -- mocha

Note the double dash, --, between percy exec and your test run command.

That's it! Now, whenever CI runs, a snapshot of the app in that state will be uploaded to Percy for visual regression testing!

For an example showing how to add Percy snapshots to an existing Puppeteer test suite, see https://github.com/percy/example-percy-puppeteer/pull/4.

Usage

percySnapshot(page, snapshotName)
percySnapshot(page, snapshotName, options)

page is the Puppeteer Page object that you want to snapshot. Required.

snapshotName is a required string that will be used as the snapshot name. It can be any string that makes sense to you to identify the page state. It should be unique and remain the same across builds. For more details on generating snapshot names, see Autogenerated snapshot names.

options is an optional hash that can include:

• widths: An array of integers representing the browser widths at which you want to take snapshots.

• minHeight: An integer specifying the minimum height of the resulting snapshot, in pixels. Defaults to 1024px.

Examples

percySnapshot(page, 'Homepage test');
percySnapshot(page, 'Homepage responsive test', { widths: [768, 992, 1200] });

Global Configuration

You can also configure Percy to use the same options over all snapshots. To see supported configuration including widths read our Configuration doc.

Contributing

1. Fork it ( https://github.com/percy/percy-puppeteer/fork )
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Add some feature')
4. Push to the branch (git push origin my-new-feature)
5. Create a new pull request

Throw a ★ on it! 😄